POSITIVE: See Research Design and Implementation Criteria Checklist below.

Research Purpose:

To quantitatively summarize the effects of moderate alcohol intake on biomarkers of risk of coronary heart disease (CHD) and to determine the projected impact of those changes on risk of CHD.

Inclusion Criteria:

MEDLINE search for all experimental studies of alcohol in humans published in English between 1965 and 1998. Medline search was supplemented with citations from review articles, meeting and symposia proceedings and the Journal of the Alcohol Beverage Medical Research Foundation and Alcohol Research. The search was restricted to the following:

Studies in individuals without diagnosed CHD, diabetes or alcohol dependence

Studies that assessed biomarkers consistently modified by alcohol and related to risk of coronary heart disease

Studies with an intervention period of at least seven days when examining lipid factors

All studies of coagulation and thrombolytic factors regardless of intervention period

Only studies that included the following information were included in the final analysis:

Number of participants

Age range of participants

Participant sex

Average dose of alcohol

Study duration

Beverage type

Change in a biomarker compared with its pretreatment measurement or compared to a comparable group of placebo or untreated participants.

Exclusion Criteria:

Studies in which participants consumed 100g or more of ethanol per day

Studies of lipid peroxidation and platelet aggregation.

Description of Study Protocol:

Recruitment

MEDLINE search for all experimental studies of alcohol in humans published in English between 1965 and 1998

MEDLINE search was supplemented with citations from review articles, meeting and symposia proceedings, and the Journal of the Alcohol Beverage Medical Research Foundation and Alcohol Research.

Predicted mean change in each biomarker after an intake of 30g alcohol per day was calculated

Previously published studies linking a change in each biomarker to risk of CHD were used to calculate the predicted relative risk (RR) of CHD that would be expected on the basis of the change in each biomarker achieved by consuming two drinks per day.

Based on the results of this meta-analysis, the change in the concentrations of HDL, fibrinogen and TG associated with an alcohol intake of 30g per day is expected to reduce risk of coronary heart disease by 24.7%.

Other Findings

For HDL:

Among five studies with average baseline HDL concentrations less than 40mg per dL, the effect of alcohol was stronger (B=0.138mg per dL) than among the 18 studies with concentrations higher than 48mg per dL (B=0.110, P=0.04).

Author Conclusion:

Results suggest that moderate alcohol intake is causally related to lower risk of CHD through alcohol-induced changes in lipids and hemostatic factors.

Reviewer Comments:

The interpretation of modification effects is not presented clearly. For example, "Among men (29 records)the coefficient for a 1g increase in alcohol was stronger (B=0.134mg per dL) than in women (three records) (B=0.095mg per dL; interaction,P=0.93)," The authors seem to be noting a difference between coefficients despite a non-significant interaction. For this reason, the results regarding effect modifications were not included. Additionally, these results are not the primary analysis.

A table of the studies included in the meta-analysis is available on-line from the BMJ with the full-text article. This abstractor included these tables when completing the Research Design and Implementation Rating Checklist and when considering the overall rating for this paper.

The authors did not explicitly state the search terms used in their description of the study methods or the number of abstracts reviewed. However, the general search terms can be inferred from the Methods discussion.

The authors do not discuss the distribution of the effect sizes of the studies included in the analysis. In addition, the variance associated with the effects observed from the studies included is not presented.

The authors do not include the standard errors of the beta-coefficients presented in the results.

Will the answer if true, have a direct bearing on the health of patients?

Yes

2.

Is the outcome or topic something that patients/clients/population groups would care about?

Yes

3.

Is the problem addressed in the review one that is relevant to nutrition or dietetics practice?

Yes

4.

Will the information, if true, require a change in practice?

Yes

Validity Questions

1.

Was the question for the review clearly focused and appropriate?

Yes

2.

Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?

Yes

3.

Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified and appropriate? Were selection methods unbiased?

Yes

4.

Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methods specified, appropriate, and reproducible?

Yes

5.

Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?

Yes

6.

Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?

Yes

7.

Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently across studies and groups? Was there appropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?

???

8.

Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels of significance and/or confidence intervals included?

Yes

9.

Are conclusions supported by results with biases and limitations taken into consideration? Are limitations of the review identified and discussed?